Voltage control



March 24, 1936. H, GRANT, JR 2,035,125

VOLTAGE CONTROL Filed Feb. 2, 1928 IN ENTOR Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE VOLTAGE CONTROL Application February 2, 1928, Serial No. 251,321

13 Claims.

The present invention relates to devices for controlling the voltage of current from a source of electricity, whereby fluctuations at the source will not be impressed across apparatus to be 5 operated by such current. There are many instances where a constant voltage is necessary for the operation of mechanism, such as fire detecting apparatus, etc., yet the location of the apparatus frequently is such that a current supln ply of this character is not available.

The invention has for its object the provision of a means for controlling the voltage of current from a source of electrical supply to maintain a constant value thereof across desired terl5 minals, in spite of relatively great variations of the voltage at the source. With this condition existing at the terminals, the accuracy of indications of detecting apparatus or of the operation of any desired mechanism is unfailing.

go The underlying principle involved in the maintaining of a constant voltage supply consists in creating conditions in a given device which serve to counteract the disturbance set up therein by the varying voltage supplied to 25 the device. These conditions are created by the varying voltage and vary therewith tolerating no variation in the resulting voltage supplied.

The invention will be understood more fully in connection with the following description and 30 the accompanying drawing, wherein:

Figure l is a conventional view showing the electrical circuits and connections of a device constructed in accordance with the present invention.

35 Figure 2 shows a modified form of the invention using three-element vacuum tubes in place of the two-element tubes used in the form shown in Figure 1.

Referring to Figure l, the primary of a trans- 4 former T is shown at T1 and the secondaries thereof at S1, S2, S3, S4, S and S6. The line voltage EL of the source is impressed across the primary coil T1 of the transformer T. This voltage, in practice, may vary between wide limits without affecting the constant voltage secured by the operation of the device described. The three secondaries S1, S5 and Se supply current for heating the filaments of vacuum tubes or 0 thermionic valves V1, V2, V3 and V4, and the secondaries S2, S3 and S4 supply plate voltages to vacuum tubes or thermionic valves V4, V1 and V2, respectively. The filament circuits are designated by the characters s1, s5 and s6, respec- :55 tively, variable resistances r1, T2 and 1; being provided for varying the voltages across the filaments of the respective tubes.

Vacuum tubes or thermionic valves V1 and V2 are two-element tubes serving together as a full-wave rectifier, the rectified voltage being 5 impressed on the plate of the three-element vacuum tube or valve V3. Vacuum tube or thermionic valve V4, also a two-element tube, serves as a half-wave rectifier and impresses its voltage ET across the resistance R. The plate voltages of tubes V1 and V2, supplied by the transformer secondaries S3 and S4, the filament temperatures which are dependent upon the secondary S5, and the resultant output of the tubes V1 and V2 all vary with the changes in the line voltage EL, and any voltage obtained directly from these tubes also varies. The rectified unfiltered output of the tubes V1 and V2 is applied to the plate of the three-element vacuum tube V: through wire 03. The current passing through V3, varying with the plate voltage, will change in accordance with the variations in the. line voltage.

In order that these changes may be corrected, the grid of the three-element tube V3 is given a negative bias by current supplied from the tube V4, this bias changing in accordance with the variations in the line voltage EL. The proper bias Eg is obtained on the grid of the tube V3 with respect to its filament by connecting the filament into the proper point of the resistance R by means of a wire V4. To provide an initial adjustment between the wire or and the resistance R, a variable contact is provided between these elements as indicated in the drawing. With the terminals of the three-element tube V3 connected as described above, the changes in the current through the tube which are caused by reason of the variations in the plate voltage will be counteracted by the corresponding changes in the grid bias afforded through the supply from the tube V4 and resistance R. The initial adjustment of the amount of resistance R from which is obtained the grid voltage for the grid of the tube V3 should be such that the grid voltage is changed in the proper amount when it varies and the connections should be such that the current flow is in the proper direction. The voltage across that portion of the resistance R from which is obtained the grid voltage for the grid of tube V3 is indicated at E and the resultant output voltage of the three-element tube V3 is impressed across the resistance R2. This voltage will be constant for all values of the line voltage E1. and may be used for the constant voltage supply ER. The resistance R2 is connected through 51 with the point of zero potential between the transformer secondary coils S3 and S4 and the resistance R is connected to the secondary coil S2 through the wire 52.

It will be seen that the variations in the plate voltage of the tube V3 and the grid voltage thereof occur'simultaneously and'in theopposite di-' rections, that is, inversely. The proportionate changes of each are such that the resultant voltage will be constant. similar or proper characteristics, and the proper initial adjustments of the resistances, the voltage Eg will change the correct amount to counteract the changes in the plate voltages and filament temperature of the tube V3. With this: condition, the resulting voltage E13,.and. the corresponding current remain absolutely constant regardless of changes in the line voltageEa.

I .A modified form of the invention is shown in Figure 2, wherein three-element vacuum tubes are. used in place of the two-element tubes or valves V1 and V2 shown in Figure 1. The transformer T; in thiscase, is provided with only five secondaries S1,,S2, S3, S4, and S5. The primary T1 receives the line voltage E1. as'in the previous design. Three-element vacuum tubes V11 and V12 are connectedto the respective transformer secondaries inthe manner described hereinafter.

The rectifier tube V4 is the same as used in Figure 1, being connected to the transformer secondaries S1 and S2 by the wires 81 and $2. The resistance 1'1 is connected in the filament circuit in and serves as a means for varying the heating of the filament of V4. The plate of the tube V4 is connectedto. the resistance R and. the coil S2 by Wire 82. the resistance R may be tapped by means of the wire D4 which is connected to the resistance R2.

The filaments, of tubes V11 and V12 are heated. by currentfrom the secondary. S5 which is con-. nected through wires 85 and resistance T2 to the filaments of these tubes. The secondaries S3 and S4 are-connected together and at the point so that this potential produces a negative bias vuponeach grid. In order that the fluctuations across the plate circuits of the three-element tubes V11 and. V12 maybe counteracted by corresponding, fluctuations in the opposite direction andof the same magnitude on the grid terminals,

the resistances are varied initially to provide the desired characteristics.

A's describedin connection with the circuits shownin Figure 1, the fluctuations on the plates of the three-element tubes V11 and V12 will be counteracted in view of the fact that these tubes have a negative grid bias which varies in such manner that the current flowing through the tubeswill always remain constant. When the plate voltage increases the negative grid bias increases to counteract such change in the plate voltage... The resulting voltage ER across the resistance R2 always remains constant.

It is tobe, understood that any of. the well known expedients now available for heating the By the choice of tubes of- As in the diagram shown in Figure l,

filaments etc. may be utilized in the system described above. The invention may be applied to either A. C. or D. C. line voltage by substitutions well known in the art and other changes may be made without departing from the scope of the invention as set forth in the appended claims.

I claim as my invention:

1. The method of providing a: constant direct current outputvoltage which consists in rectifying a varying source of alternating current, rectifying a second supply which varies inversely as the firstrectified supply to secure a potential, adjusting the magnitude of one of the supplies initially; and combining the two supplies electrically whereby 'a constant direct current potential will be obtained.

2. The method of providing a constant direct current output voltage which consists in rectifying avarying source of alternating current, impressing the rectified current upon the plate of. a three-element vacuum tube, rectifying a second supply from the varying source, the last named supply varying in proportion to thefirst rectified supply, and impressing the second supply on the grid of'the three-element tube to give the latter a negative bias with respect to the filament of the three element tube, whereby the plate current will be maintained constant.

3. The method of providing a constant direct current output voltage which consists in rectifying a varying source of alternating current, impressing the rectified current upon the plate of a three-element vacuum tube, rectifying a second supply from the varying source, the last named supply varying in proportion to the first rectified supply, adjusting the voltages of the two supplies initially, and impressing the second supply on the grid of the three-element tube to give the latter a negative bias with respect to the filarnentof the three element tube, whereby the plate current will be maintained constant.

4. Means for maintaining a constant voltage comprising a varying alternating voltage source, means to rectify the source'to produce a direct current varying in proportion to the variation of the source, means to rectify a second supply from the source to secure a potential which varies proportionately thereto, and means for impressing 1eilectrically the second rectified supply upon the rst.

5. Means for maintaining a constant voltage comprising a varying alternating voltage source, a three-element vacuum tube, means to impress the source upon the plate of the three-element tube, means for rectifying a second supply which varies in accordance with the variations impressed upon the plate, and means to impress the second supply upon the grid of the three-element vacuum tube to providethe latter with a negative bias with respect to the filament.

6. Means for maintaining a constant voltage comprising a varying alternating voltage source, a three-element vacuum tube, a two-element thermionic valve, a pair of two-element thermionic valves, means to transform the current from the. source, means to impress portions of the transformed current across the pair of valves to cause their half-wave rectification to produce a full-wave rectification, means to impress another portion of'the transformed current across the first valve, means to supply the output of the pair of valves to the plate of the three-element tube,

means to produce a negativegrid bias on the grid of the three-element tube from the first named valve, and means to supply voltage from the threeelement tube to an external circuit.

7. Means for maintaining a constant voltage comprising a varying alternating voltage source, a three-element vacuum tube, a two-element thermionic valve, a pair of two-element thermionic valves, means to transform the current from the source, means to impress portions of the transformed current across the pair of valves to cause their half-Wave rectification to produce a full-wave rectification, means to impress another portion of the transformed current across the first valve, means to heat the filaments of all of the valves from a portion of the transformed current, means to supply the output of the pair of valves to the plate of the three-element tube, means to produce a negative grid bias on the grid of the three-element tube from the first named valve, and means to supply voltage from the three-element tube to an external circuit.

8. Means for maintaining a constant voltage comprising a varying alternating voltage source, a three-element vacuum tube, a two-element thermionic valve, a pair of two-element thermionic valves, means to transform the current from the source, means to impress portions of the transformed current across the pair of valves to cause their half-Wave rectification to produce a full- Wave rectification, means to impress another portion of the transformed current across the first valve, means to supply the output of the pair of valves to the plate of the three-element tube, means to supply a portion of the output of the first valve to the grid of the three-element tube to produce a negative bias thereon, and means to supply voltage from the three-element tube to an external circuit.

9. Means for maintaining a constant voltage comprising a varying alternating voltage source, a three-element vacuum tube, a two-element thermionic valve, a pair of two-element thermionic valves, means to transform the current from the source, means to impress portions of the transformed current across the pair of valves to cause their half-wave rectification to produce a full Wave rectification, means to impress another portion of the transformed current across the first valve, means to supply the output of the pair of valves to the plate of the three-element tube, means to supply a portion of the output of the first valve to the grid of the three-element tube to produce a negative bias thereon, means to vary the voltage of the first valve impressed on the grid, and means to supply voltage from the threeelement tube to an external circuit.

10. The method of providing a constant direct current output voltage which consists in rectifying a varying source of alternating current, rectifying a second supply from the source independently of the first rectified supply to secure a potential varying inversely as the first rectified supply, and combining the two supplies electrically, whereby a constant direct current potential will be obtained.

11. The method of providing a uni-directional voltage of constant magnitude, from a source of alternating current voltage varying in magnitude which comprises opposing the changes in magnitude of a uni-directional primary voltage derived from said source with a second uni-directional voltage which is derived from said source independently of the primary voltage circuit and which varies inversely with respect to the primary voltage, the magnitude of one of the voltages being capable of adjustment to a desired value.

12. The method of providing a uni-directional voltage of constant magnitude from a varying source of alternating current which comprises producing a uni-directional primary voltage from such source varying in proportion thereto, producing a second uni-directional voltage from the source independently of the primary voltage varying inversely as the variations of the primary voltage, adjusting the magnitude of one of the voltages to a desired value, and combining the two voltages to produce a uni-directional voltage supply of constant magnitude.

13. Means for maintaining a uni-directional voltage of constant magnitude comprising a varying alternating current voltage source, means to produce a uni-directional primary voltage from the source, means to produce a second unidirectional voltage from the source independently of the primary voltage circuit and varying inversely as that of the source, means to adjust the magn tude of one of the voltages to a desired value, and means to combine the two, whereby a unidirectional voltage supply of constant magnitude is obtained.

HARRY CAMPBELL GRANT, JR.

CERTIFICATE OF CORRECTION.

Patent No. 2,035,125. March 24, 1936.

HARRY CAMPBELL GRANT, JR.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 12, claim 1, strike out the words "to secure a potential" and insert the same after "supply" in line 11; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of April, A. D. 1936.

Leslie Frazer (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,035,125. March 24, 1936.

HARRY CAMPBELL GRANT, JR.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2., second column, line 12, claim 1, strike out the words "to secure a potential" and insert the same after "supply" in line 11; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of April, A. D. 1936.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

